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 *     General Public License Version 2 only ("GPL") or the Common Development
 *     and Distribution License("CDDL") (collectively, the "License").  You
 *     may not use this file except in compliance with the License.  You can
 *     obtain a copy of the License at
 *     https://github.com/payara/Payara/blob/main/LICENSE.txt
 *     See the License for the specific
 *     language governing permissions and limitations under the License.
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 *     When distributing the software, include this License Header Notice in each
 *     file and include the License file at legal/OPEN-SOURCE-LICENSE.txt.
 *
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 *     The Payara Foundation designates this particular file as subject to the "Classpath"
 *     exception as provided by the Payara Foundation in the GPL Version 2 section of the License
 *     file that accompanied this code.
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package fish.payara.microprofile.faulttolerance.state;

import java.io.Serializable;
import java.time.ZonedDateTime;
import java.time.temporal.ChronoUnit;
import java.util.concurrent.atomic.AtomicLong;

/**
 * Represents the state its time amount and since when this is in charge.
 * @author Sven Diedrichsen
 */
class StateTime implements Serializable {

    private static final long serialVersionUID = 1;

    private final CircuitBreakerState.CircuitState state;
    private ZonedDateTime since;
    private final AtomicLong nanos;

    StateTime(CircuitBreakerState.CircuitState state) {
        this.state = state;
        this.since = ZonedDateTime.now();
        this.nanos = new AtomicLong(0);
    }

    /**
     * State that this represents.
     *
     * @return The state.
     */
    CircuitBreakerState.CircuitState state() {
        return this.state;
    }

    /**
     * True if this StateTime represents the provided {@link CircuitBreakerState.CircuitState}
     *
     * @param state The state to compare to.
     * @return State equals.
     */
    boolean is(CircuitBreakerState.CircuitState state) {
        return this.state.equals(state);
    }

    /**
     * The current sum of nanos.
     *
     * @return Sum of nanos.
     */
    long nanos() {
        return nanos.get();
    }

    /**
     * Updates the sum of nanos.
     *
     * @return The updates sum of nanos
     */
    long update() {
        ZonedDateTime now = ZonedDateTime.now();
        long result = this.nanos.addAndGet(ChronoUnit.NANOS.between(this.since, now));
        this.since = now;
        return result;
    }

    /**
     * Sets the time for the state to now.
     */
    void reset() {
        this.since = ZonedDateTime.now();
    }

}
